Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
2000-03-16
2003-04-15
Nguyen, Nam (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S196280, C204S275100
Reexamination Certificate
active
06547938
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an anodizing apparatus, an anodizing system, a substrate processing apparatus and method, and a substrate manufacturing method.
BACKGROUND OF THE INVENTION
Porous silicon was found by A. Uhlir and D. R. Turner who were studying electropolishing of single-crystal silicon biased to a positive potential in an aqueous solution of hydrofluoric acid.
Later, to exploit excellent reactivity of porous silicon, application of porous silicon to the element isolation process in manufacturing a silicon integrated circuit was examined, and a full isolation technology (FIFOS: Full Isolation by Porous Oxidized Silicon) using a porous silicon oxide film was developed (K. Imai, Solid State Electron 24, 159, 1981).
Recently, an applied technology to direct bonding has been developed in which a silicon epitaxial layer is grown on a porous silicon substrate, and the substrate is bonded to an amorphous substrate or single-crystal silicon substrate via the oxide film (Japanese Patent Laid-Open No. 5-21338).
As another application example, porous silicon has received a great deal of attention as a photoluminescence or electroluminescence material that emits light by itself (Japanese Patent Laid-Open No. 6-338631).
A conventional anodizing apparatus for manufacturing a substrate having a porous silicon layer will be described below.
FIG. 20
is a view showing the arrangement of a conventional anodizing apparatus (Japanese Patent Laid-Open No. 60-94737). In this anodizing apparatus, anodizing tanks
1902
a
and
1902
b
made of Teflon (tradename of du Pont in the U.S.A) as a material with HF resistance are arranged to sandwich a silicon substrate
1901
from both sides. The anodizing tanks
1902
a
and
1902
b
respectively have O-rings
1904
a
and
1904
b
for sealing at portions where the silicon substrate
1901
is held. The anodizing tanks
1902
a
and
1902
b
have platinum electrodes
1903
a
and
1903
b,
respectively. After the silicon substrate
1901
is sandwiched by the two anodizing tanks
1902
a
and
1902
b,
the anodizing tanks
1902
a
and
1902
b
are filled with HF solutions
1905
a
and
1905
b,
respectively. In this state, a DC voltage is applied between the electrodes by setting the platinum electrode
1903
a
as a negative electrode and the platinum electrode
1903
b
as a positive electrode. The silicon substrate
1901
is anodized, and a porous silicon layer is formed on the negative-electrode-side surface of the silicon substrate
1901
.
In such conventional scheme of vertically holding a silicon substrate and anodizing it, a gas (e.g., hydrogen gas) generated by the anodizing reaction may stay on the surface of the silicon substrate for a long time or rise along the surface of the silicon substrate. In this case, the track of gas remains on the surface of the porous layer formed on the silicon substrate. This makes the porous layer nonuniform to result in poor quality and a decrease in yield and productivity. Hence, a demand has arisen for introduction of a new scheme of preventing a gas generated by the anodizing reaction from adversely affecting anodizing.
To obtain high quality and productivity for substrates having a porous silicon layer, it is important to reduce contamination of a silicon substrate during anodizing, and reduce contamination of a silicon substrate during a series of processes including anodizing and associated processes (e.g., washing and drying).
To increase productivity of substrates having a porous silicon layer, it is also important to increase the speed of the series of processes including anodizing and associated processes.
Additionally, in consideration of the recent tendency of an increase in diameter of silicon substrates, it is also important to propose a scheme capable of easily coping with the increase in diameter.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation, and has as its object to provide a new anodizing scheme.
More specifically, it is an object of the present invention to, e.g., prevent any influence of a gas generated by an anodizing reaction.
It is another object of the present invention to, e.g., prevent any contamination of a substrate to be processed.
It is still another object of the present invention to, e.g., increase the speed of a series of processes including anodizing and associated processes.
It is still another object of the present invention to, e.g., facilitate to cope with an increase in diameter.
According to the first aspect of the present invention, there is provided an anodizing apparatus for anodizing a substrate, characterized by comprising a holding portion for substantially horizontally holding the substrate to be processed, a negative electrode arranged above the substrate to oppose the substrate, a positive electrode arranged under the substrate, and an anodizing tank for filling a space between the substrate and the negative electrode with an electrolyte, wherein the negative electrode has a function of preventing a gas from staying on a lower side.
In the anodizing apparatus according to the first aspect of the present invention, for example, the negative electrode preferably has a degassing hole for preventing the gas from staying on the lower side.
In the anodizing apparatus according to the first aspect of the present invention, for example, the positive electrode preferably supplies a current to the substrate to be processed while being in direct contact with a lower surface of the substrate in anodizing.
In the anodizing apparatus according to the first aspect of the present invention, for example, of the positive electrode, at least a portion which comes into contact with the substrate to be processed is preferably formed from a semiconductor material.
Preferably, the anodizing apparatus according to the first aspect of the present invention further comprises, e.g., an electrode support portion supporting the positive electrode, and the electrode support portion has a mechanism for attaching/detaching the positive electrode.
In the anodizing apparatus according to the first aspect of the present invention, for example, the positive electrode preferably has a chuck mechanism for chucking the substrate to be processed.
In the anodizing apparatus according to the first aspect of the present invention, for example, the chuck mechanism preferably comprises a vacuum chuck mechanism.
In the anodizing apparatus according to the first aspect of the present invention, for example, the holding portion preferably holds a peripheral portion of the lower surface of the substrate to be processed.
In the anodizing apparatus according to the first aspect of the present invention, for example, the holding portion preferably has a chuck portion for holding the substrate to be processed by chucking a peripheral portion of the lower surface of the substrate.
In the anodizing apparatus according to the first aspect of the present invention, for example, the anodizing tank preferably has an opening portion at a bottom portion and can be filled with a liquid when the holding portion holds the substrate to be processed.
In the anodizing apparatus according to the first aspect of the present invention, for example, the positive electrode preferably comes into contact with the lower surface of the substrate to be processed, inside the opening portion.
The anodizing apparatus according to the first aspect of the present invention preferably further comprises, e.g., an electrode elevating mechanism for vertically moving the positive electrode.
The anodizing apparatus according to the first aspect of the present invention preferably further comprises, e.g., a rotary driving mechanism for rotating the substrate to be processed substantially in a horizontal plane to remove the liquid sticking to the substrate.
The anodizing apparatus according to the first aspect of the present invention preferably further comprises, e.g., a rotary driving mechanism for, after the substrate is released from the holding portion, rotating t
Matsumura Satoshi
Yamagata Kenji
Canon Kabushiki Kaisha
Morgan & Finnegan , LLP
Nguyen Nam
Nicolas Wesley A.
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